It is known that during milling cutting operations the length of the cutting edge is directly related to the vibrations induced in the milling cutter and the workpiece and the energy requirements in carrying out the cutting operation. These vibrations give rise to so-called "chatter". In other words, "chatter" tends to increase with increasing length of the cutting edge.
The vibrations and consequent "chatter" arise out of the forces exerted on the cutting insert and especially on the cutting rake surface thereof by the chip which is formed and the greater the width of the chip, the greater will be the exerted forces. With a view to decreasing these vibrations and "chatter", it is known to employ milling cutters having cutting inserts with relatively short cutting edges, the inserts being so orientated with respect to the tool holder and with respect to each other that the cutting paths of the cutting edges of successive cutting inserts overlap. In this way each relatively short cutting edge gives rise to a chip of relatively narrow width, the overlap between the cutting edges of successive cutting inserts ensuring that relatively smooth milling is attained.
In practice, however, this proposal is not found to be effective, requiring as it does the careful preliminary orientation of correctly designed cutting inserts on and with respect to the tool holder.